The roof

How did people create such magnificient buildings a few centuries ago without our modern technology? I can't even imagine how exhausting this process was. I know that Michaelangelo spent four years lying on his back to paint the Sistine Chapel.
I don't know about the countless paintings and mosaics in St Peter's cathedral in Vatican but it must have taken years just to decorate the roof. Well, it was definitely worth it 'cause it makes the impression!